UA34832A - Method for assessing parameters of blood pressure - Google Patents

Abstract

The invention relates to the medicine and may be used for the examination of hemodynamics in the patients with the cardiovascular pathology, the pathology of the kidneys, the brain, and the endocrine system. The method for assessing the parameters of the blood pressure provides for the reography of the area of the limb under the cuff.

Description

The invention relates to medicine and can be used in the study of hemodynamics in patients with pathology of the cardiovascular system, kidneys, brain, endocrine system.

The main drawback of most of the proposed methods of determining blood pressure (BP) parameters is the significant inaccuracy and lack of completeness of the information obtained, the impossibility of determining, except for the values of systolic and diastolic BP (BP,

DAT), also known as medium dynamic blood pressure (SDT). The importance of a precise definition of this parameter is necessary for the calculation of an important indicator of hemodynamics - total and specific peripheral vascular resistance (PPSO, PPSO).

In scientific works and in practical cardiology, the SDT is determined by a calculation method based on the SAT and DAT data, using the Hickam, Wetzler-Boger or Simoni formulas.

The surveyor receives rather inaccurate information.

Direct determination of SDT can be carried out by the oscillographic method proposed by M.M. Savitskyi (1). It consists in registering not the curve of vascular oscillations itself, but their derivative, obtained with the help of a differential manometer, the output pneumatic signal of which is the difference of the directly determined

BP and pressure in the damper chamber connected to the same pressure source. With greater sensitivity, the method was called tachoscillographic. However, it is not always possible to clearly interpret the received tachoscillograms. The difficulty of visually choosing the first negative tooth among several for the identification of DAT, determining the phenomenon of "aging" from several similar ones, as well as

SAT, for recognition of which it is necessary to synchronously record the sphygmogram of the artery located below the cuff, limits the use of this method. In addition, to implement the method, it is necessary to use a complex mechano-optical device with a linear characteristic of pressure growth in the inflatable cuff, as well as the possibility of obtaining only time-delayed information (after developing and drying the photo paper, analyzing the received tachoscillograms by an experienced specialist).

There is a known method of determining blood pressure parameters in young children (prototype), which allows determination of systolic and diastolic blood pressure based on the differential curve of the compression reobarogram. However, this method does not make it possible to determine the SDT. In addition, the authors suggest the location of potential electrodes, parallel on both sides above the brachial artery under the cuff, which gives limited information due to uneven compression of the artery under the cuff, as well as uneven electrode-skin contact (Fig. 21.

The purpose and task of the invention is to increase the accuracy of determination of blood pressure parameters - systolic, mid-dynamic, diastolic. The purpose of the invention is achieved by conducting synchronous registration of pressure changes - a decompression barogram and a differential rheogram of the same part of the limb on which the cuff is applied, the maximum of the first high-amplitude wave of the rheocomplex is recorded on it, then one of the highest rheocomplexes with the "notch" located closest in time to the main wave and maximally opposite to it and the first main wave of the rheocomplex, which does not change in amplitude, and on the barogram corresponding to these three points is the value of systolic and medium dynamic and diastolic blood pressure.

The method is carried out in the following sequence. A pneumatic cuff, for example, from a sphygmomanometer is stitched from the inside along the canvas with 4 strips of electrodes made of conductive fabric, which are respectively connected to the input of a rheoplethysmograph, for example, RPG-2-02 (Fig. 1). The output of the rheoplethysmograph "diff." connected to one of the channels of the recording device, for example, a 2-channel electrocardiograph. A device that registers the pressure in the inflatable cuff is connected to the second channel - a pneumatic electrical transducer (Fig. 2). Air is pumped into the cuff above the systolic pressure with a pear or a compressor. Then the valve is opened and air is released from the system at a speed of 2-3 mm/sec. Synchronously start the tape recorder (ECG) with the speed of the belt moving mechanism of 10-25 mm/sec. The barogram is pre-calibrated.

With compression above the systolic blood pressure, a complete cessation of blood flow is observed in the area under the cuff, where the potential electrodes are located, and for this reason, the periodic component of the change in impedance, which depends on the movement of blood through the vessels, is not detected, and on the rheogram it corresponds to a straight line or small fluctuations without a pronounced periodic pattern. As the decompression progresses, the moment comes when the intra-arterial pressure is able to exceed the applied external pressure, at least during a short period of heart systole. During this period of time, the parallel overcoming of blood flow resistance begins to influence the impedance value, and the first rheocomplexes appear on the rheogram, the clear definition of which is reflected by the differential curve. This indicates that in the space between the potential electrodes in the area of the limb under the cuff (its middle part), where the maximum compression by the applied external pressure occurs, a partial opening of the arteries takes place in a short period of time, which corresponds to the beginning of listening to Korotkov's tones. It is accepted to consider the systolic decompression pressure at the moment of listening to the first Korotkov tone. which corresponds to the first high periodic rheocomplex (Fig. 3). With further decompression, the artery continues to open more and more, and the veins of the distal part of the limb still remain clamped, since their internal pressure is lower than the arterial pressure. Therefore, a kind of closed capacity is formed in the distal segment of the limb, which is connected to the blood stream by a relatively small passage hole, which is similar to a hydraulically regulating damping system, inside which a pressure equal to the average dynamic blood pressure is established. In the course of further decompression, when the applied external pressure equalizes with the average dynamic blood pressure and continues to slowly decrease, then during a certain period of time of the pulse wave, blood from the distal part of the artery is able to overcome the compression of the vessel by the cuff and penetrate retrogradely. This short-term dilation of the artery occurring during or immediately after the short-term opening of the artery under the cuff can induce a drop in impedance, which is particularly noticeable on the differential curve.

But the impedance is quickly equalized, since a very small transition of blood from the distal to the proximal part of the limb is enough for the pressure in the artery on the two sides of the cuff to equalize, and the pressure in the cuff to squeeze the vessel again. The identification of the SDT is carried out according to the above data against the background of the highest tooth (there may be several of them), but the one of them is determined, which has another sign of "notch" - the closest in time to the top of the main tooth, a. is also directed in the opposite direction to it as much as possible (Fig. 3).

As the decompression progresses, the constricted artery. gradually becomes passable for the entire period of the cardiac cycle, although not the entire size of the lumen of the vessel, because the applied pressure affects it. For this reason, the phenomena described above are no longer observed. At the same time, the phenomena of "jaggedness" observed on 2-4 complexes disappear on the differential rheogram, the amplitude of the main wave, the shape of its descending part decreases. At the moment of equalization of pressure in the cuff with the level of DBP, periodic changes in impedance are caused not so much by the effect of artificial compression of blood vessels, but by their normal physiological pulsation. Therefore, as a rule, it is observed on the differential rheogram. a sequence of rheocomplexes with the same amplitude of the main teeth. The first of the consecutive, equal in amplitude waves will correspond to the pressure in the cuff equal to the diastolic blood pressure (Fig. 3).

Example 1. Patient P., 32 years old. Diagnosis: vegetative-vascular dystonia of the cardiac type with vascular paroxysms. SN O Art.

Table 1 mon WINTER

Sbeyunesnetnntktnnne Ge! || at 7 47/

Theosototevntesennnmy || 7/7 000 eeeeyunnnnui 000 re) i|)776

DRBG - decompression reobarogram.

The biggest difference in the value of SDtT, between the calculation method, according to Hickem's formula. SDT-(SAT-DAT)UZADAT and the proposed method is - 4.7 mm Hg. Art.

If we take into account the error when determining one of the three complexes on the tachoscillogram, where identical phenomena of "crushing" are observed, by tachoscillography - the basic method of SDT - it will be 5-6 mm Hg. Art., as pointed out by the author M.M. Savytskyi. (HER, Article 184.

According to the data of the proposed method, the possible error in determining SDT is 1-2 mm Hg. Art.. at the same time, it largely depends on the speed of decompression.

The exact determination of SDT is important for the calculation of one of the three main indicators of hemodynamics: stroke volume (UCB), volume of circulating blood (CCB) and total (specific) peripheral resistance (SPSO, PPSO). There are quite accurate ways to determine the first two indicators. Having a complete set of these three refined data, it is possible to more reliably assess hemodynamics, especially during the selection of pharmacological means of vasoactive action.

Example 2. Patient R., 56 years old. Diagnosis:

Essential hypertension of the 2nd century, SI Hist.

Table 2 and

Sfimomanometricnimsa Korotov Mo | | yuyu in peoyutnetnisyunnnym t same senia ren

Now we calculate zpso according to two methods: tachoscillographic according to M.M. Savitsky. and proposed by us (DRBG), having the value of the minute blood volume (MVV), determined by the method of tetrapolar thoracic rheography (TPGR) according to the method

KybrisecK, which is 4.2 liters per minute. zpso - 1333ХСОДtХХбо / ХОК, where 1333 is the conversion factor mm Hg. in dynes/cm, 60 - takes into account the conversion from ml per minute to ml per second |ZI.

After the appropriate transformations, the formula acquires the following content: zZpSO-sSDtXx80/HOKdinhex cm 5 SDT in mm Hg, ahoKvl per min.

Let's calculate the error of ZPSO according to the tachoscillographic method from 120-126 mm Hg (1) and the proposed - from the found values of SDT 130-131 mm Hg. (2).

Tachooscillographic method according to M.M. Savitsky:

ZPSO (1) - 2286 dynes x s x cm'5, ZPSO (1) - "2400 dynes x s x cm'5

A E114dyn x s x cm'5

ZpSO/L1/-2286 dynes x s x cm'5, ZPSO/1/5 52400 dynes x s x cm'5

A E14dyn x s x cm'5

According to the proposed method of DRBG:

ZPSO /2/ 5 2476 dyn x w x cm'5, ZPSO /2/ 2495 dyn x w x cm'5

A 19dyn x s X cm 5

Therefore, the error of the proposed method is an order of magnitude lower than that of the basic method.

For a comprehensive evaluation of the hemocirculation of UOC, BCC, ZpPSO, especially in the kinetics of physical and pharmacological tests, the application of the proposed method is extremely necessary.

The advantage of the proposed method over the known ones is the possibility, first of all, to determine with an accuracy of 1-2 mm Hg, in addition to the traditional indicators of blood pressure, the main and value - medium dynamic, and secondly, the simplicity of the technical solution of using the cuff as a simultaneous compression-decompression chamber, pressure sensor and electrodes for measuring impedance.

SOURCES

1. M.M. Savitsky. Biophysical principles of blood circulation and clinical methods of determining hemodynamics. L., 1963, 402 p. 2. A.S. Mo. 1266622 USSR, 1981. 3. T.S. Vinogradova. Instrumental method of research of the cardiovascular system! / directory /. M., "Medicine", 1986, 382 p.

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Claims (1)

The method of determining blood pressure parameters by means of rheography of the part of the limb under the cuff, which is distinguished by the fact that simultaneous registration of pressure changes is carried out - a decompression barogram and a differential rheogram of the same part of the limb on which the cuff is applied, the maximum of the first high-amplitude wave of the rheocomplex is recorded on it, then one of of the highest rheocomplexes with a "notch", located closest in time to the main wave and the first main wave of the rheocomplex directed as far as possible opposite to it, which does not change in amplitude, but corresponds to these three points on the barogram, the values of systolic, average dynamic and diastolic blood pressure .